When the easiness of a one-hand operation is emphasized, a screen of a touch panel display of a tablet device (e.g., a smart phone) is required to have a size enabling the thumb to touch any point on the screen in a state where the tablet device is grasped by one hand. Meanwhile, when the easiness of a visual recognition of displayed contents is emphasized, the screen size is required to be large.
A technology exists, in which even when the screen size is large, in order to facilitate the one-hand operation, a screen image displayed on the screen is reduced overall, and the reduced screen image is displayed at a position where the operation by the thumb is easily performed. Also, a technology exists, which determines a region where the operation by the thumb may be performed, in order to determine a region where the reduced screen image is to be displayed.
Related techniques are disclosed in, for example, Japanese Laid-Open Patent Publication No. 2013-030050 and Japanese Laid-Open Patent Publication No. 2014-179877.
However, the technologies require a display change operation such as tapping a specific icon, in order to change between displaying and not displaying the reduced screen image. When the display change operation is frequently required, the user experience may be deteriorated. Further, the reduction of the screen image may cause an erroneous operation such as tapping an icon nearby an intended icon.